UM10788 User manual for I²C-bus RTC demo board OM13515 User manual

Transcription

UM10788
User manual for I²C-bus RTC demo board OM13515
Rev. 2 — 4 August 2014
User manual
Document information
Info
Content
Keywords
PCF85063, OM13515, evaluation, demo board, how to get started, I2Cbus, RTC, Real-Time Clock, tuning
Abstract
User manual for the evaluation board OM13515. It uses the low power
RTC PCF85063AT with I2C-bus interface
UM10788
NXP Semiconductors
Revision history
Rev
Date
Description
v.2
20140804
Second revision
v.1
20140620
New user manual, first revision
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
UM10788
User manual
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2014. All rights reserved.
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1. Introduction
The PCx85063 are a family of CMOS Real-Time Clocks (RTC) and calendar optimized
for low power consumption. Different features sets are available.
The OM13515 is the ideal evaluation/demo board to use in the design phase of any
project, just power and I2C-bus must be applied.
Separate demo boards and user manuals are available for
RTC PCF85063TP/PCF85063ATL – OM11059A and UM11698
RTC with SPI-bus PCF85063BTL – OM11059 and UM10699
2. Key features
There are four RTC variants of the PCF85063x RTC with I2C-bus:
PCF85063AT, PCF85063ATT – enhanced functionality with I2C-bus interface
PCA85063ATT – enhanced functionality with I2C-bus interface AEC-Q100 qualified
automotive grade
PCF85063ATL – enhanced functionality with I2C-bus interface with clock enable input
PCF85063TP – basic functionality with I2C-bus interface
2.1 PCx85063AT, PCF85063ATT
The PCx85063A is a Real-Time Clock with very small form factor, counting seconds,
minutes, hours, days, weekdays, months, and years.
• Electronic oscillator tuning
• RAM: 1 byte
• Package:
− PCF85063AT: SO8
− PCF85063ATT: TSSOP8
− PCA85063ATT: TSSOP8, automotive grade, −40 °C to +105 °C
• Alarm control
• Timer
• WatchDog
• Interrupt:
− every 30 s or 60 s
− alarm
− timer
− WatchDog
2
• Interface: 400 kHz I C-bus
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Fig 1.
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Block diagram of the PCx85063A
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3. Hardware set-up
3.1 General requirements for the RTCs PCx85063A
The RTC circuit just requires one external part: a tuning fork quartz as resonator. The
oscillation capacitors are integrated and therefore there is no need for external
capacitors. The quartz crystal must be placed close to the RTC circuit, avoiding long
lines which may pick up noise. Avoid any tracks with high frequency signals (fast edges)
close to the RTC, quartz, or quartz interconnect.
The interface is the standard Fast Mode I2C-bus, operating up to 400 kHz. Adjust the
values of the pull-up resistors to match the required interface speed keeping them as
high impedance as possible for power savings reasons. Ensure that the specified
minimum requirements of the hold times tLOW and tHIGH are fulfilled.
Supply voltage: The RTC is specified from 0.9 V to 5.5 V. The I2C-bus interface is
specified from 1.8 V to 5.5 V. It is recommended to have a decoupling capacitor on the
VDD-VSS rails close by.
Due to the low power consumption of below 1 μW, no precautions for heat dissipations
are required.
CLKOUT can be used to measure the frequency or be used as reference for frequency
generation with a PLL.
Fig 2.
Interfacing to the microcontroller
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3.2 Demo board OM13515
Fig 3.
Picture of demo board OM13515
The OM13515 allows easily demonstrating the operation of the PCx85063A with I2C-bus
interface. No need to solder the tiny package to a breadboard 100 mil connector for
straight forward connections.
To visualize the interrupt an LED (D1) is mounted. To minimize the power consumption it
can be switched off by removing the jumper J2.
To measure the current consumption just replace jumper J1 by a µA-meter.
The market offers quartzes with different load capacitances: CL= 12.5 pF is most
common, CL= 7 pF as used on the board, offers however lower power consumption.
Straight forward interfacing:
• Connect supply voltage (e.g. 3.3 V): VSS to pin 1, VDD to pin 2
• Connect I2C-bus (pull-up resistor needed): SCL to pin 4, SDA to pin 3
• Connect interrupt and or CLKOUT if required
• Communicate with the RTC
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Fig 4.
OM13515 circuit diagram
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4. Graphical User Interface with OM13518 USB-I²C-bus dongle
4.1 USB-I²C dongle
Details are described in the user manual UM10789.
The OM13518 dongle is a ready to run module. It creates a virtual COM-port via an USB
connection. It provides three I²C-bus connections with 5 V option to power the application
(max 450 mA).
Power consumption: module/total: <50 mA/max 500 mA
I²C-bus clock frequency: 245 Hz – 400 kHz
USB driver for Windows: Windows XP, Windows 7, Windows 8
Size: 50 mm × 40 mm × 15 mm
Fig 5.
A) Dongle OM13518, B) connected to an evaluation board
4.2 Software GUI
The software control via a GUI allows a fast start to communicate to the different circuits.
Aside from the detailed GUI pages for the Real-Time Clocks, a UNIVERSAL
INTERFACE allows to communicate with any I²C-bus device by entering directly the hex
codes. Example: s A2 28 p
Where s stands for the I²C START and p for the I²C STOP condition.
There are 2 GUI versions:
USB_I2C_GUI_85063TP for the PCF85063TP RTC with basic features, no alarm facility
USB_I2C_GUI_85063A
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for the full featured PCx85063A RTC
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Fig 6.
GUI-page example: Time Alarm settings
5. Software set-up
5.1 Functionality
The RTC PCx85063A is controlled via a standard Fast Mode I2C-bus interface, operating
up to 400 kHz.
Theoretically there is no lower speed limit, however a read or write access to the RTC
must be finalized within one second after initiating it, otherwise time counter increments
could be lost. During access, the time registers of the RTC are frozen and after the read
or write sequence is completed, a seconds increment is executed if required.
The clock tracks the actual time from seconds to year. It must be initially set to the
correct time of the actual time zone. The number of days per month and leap year are
corrected automatically. Leap years are assumed whenever the year is dividable by 4.
The RTC can be programmed to generate an interrupt every 30 seconds or every
60 seconds. Interrupts can also be generated by the alarm facility, the timer and the
WatchDog.
At address byte 03h a general purpose RAM byte is ideal to store temporary information.
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5.2 System testing
There is a fast mode facility to test the functionality of the RTC; it can be activated by
setting the EXT_TEST bit in the Control_1 word.
The RTC PCF85063x has a frequency tuning facility; its operation is explained in section
RTC tuning. The RTC can stay switched on all the time. There is no need to restart or
reset the clock.
5.3 Software instructions for setting the clock
5.3.1 Setting the time
Setting the clock to 3.45 pm December 15, 2014:
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I2C-bus
S
START condition
Slave address
1010 0010
address pointer to status
word 0
Register address
0000 0000
address pointer to status
word 0
Status word 0
0000 0010
set 12 hour mode and
select option for 7 pF quartz
I2C-bus
Sr
Repeated START condition
Slave address
1010 0010
R/ W = 0, write mode
Register address
0000 0100
address pointer to Seconds
register, address 4h
Seconds
0000 0000
0 seconds (clock integrity
ok  MSB OS = 0)
Minutes
0100 0101
45 min
Hours
0010 0011
PM, 3
Days
0001 0101
15th
Weekdays
0000 0001
Monday (1st day of the
week)
Month
0001 0010
December (12th month)
Year
0001 0100
(20)14
I2C-bus
P
STOP condition
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5.3.2 Reading the clock
Reading the clock (2 minutes after writing)
I2C-bus
S
START condition
Slave address
1010 0010
R/ W = 1, read mode
Register address
0000 0100
address pointer to Seconds
register
I2C-bus
Sr
repeated start condition
Slave address
1010 0011
read mode
Read register 4
e.g. 56 seconds, (clock
integrity ok  OS = 0)
Minutes
e.g. 47 (Minutes)
Hours
e.g. 23 (PM, 03h)
Days
e.g. 15 (15th)
Weekdays
e.g. 01 (Monday)
Month
e.g. 12 (December)
Year
e.g. 14 (20)14
I2C-bus
P
STOP condition
6. RTC tuning
6.1 Frequency tuning
The 32 kHz quartzes are typically sold with a tolerance at room temperature of either
±10 ppm or ±20 ppm. 11.5 ppm corresponds to 1 s/day.
The quartzes require a characteristic load capacity of either 7 pF or 12.5 pF. Oscillators
utilizing 7 pF quartzes feature slightly lower power consumption, where the quartzes of
12.5 pF have largest production quantities. Program the CAP_SEL bit in register
Control_1 accordingly. The tracks between quartz and RTC represent also some
parasitic capacitances and must be kept short.
The PCF85063 has a tuning facility where above tolerances can be compensated.
Tuning procedure:
• Measure the 32xxx Hz (f) signal at the CLKOUT pin.
• The offset is calculated in ppm as
6
Δf[ppm] = 10 × (f - 32768) / 32768
• Consult the offset table in the data sheet. Take the correction value and write it into
the register 02h.
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• The correction is done by means of inhibition or addition: the oscillator runs at
constant speed, then every 2 hours (mode 0) 1 second is corrected to by making it
shorter or longer. This is not easily visible at the CLKOUT.
• Corrections can also be applied every 4 minutes by using mode 1. This mode will
consume slightly more power.
The 32 kHz quartzes are of the type tuning fork and feature a parabolic frequency
response over temperature. When the application is dominantly used over a limited
temperature range, it is often helpful to tune the frequency to be slightly higher at the
turn-over point. The error around 25 °C (clock goes too fast) is then compensated during
the time when temperature is lower or higher. For example, for operation between 5 °C
and 45 °C, tune the clock 8 ppm faster than the value for 25 °C would be. (Fig 7)
(1) Characteristic if tuned to 32.768 kHz at 25 ºC.
(2) Characteristic if tuned with the positive offset Δfoff.
Fig 7.
Temperature averaged over application range 5 °C to 45 °C
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7. References
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[1]
AN11247 - Improved timekeeping accuracy with PCF85063, PCF8523 and
PCF2123 using an external temperature sensor
[2]
UM10301 - User Manual for NXP Real Time Clocks PCF85x3, PCA8565 and
PCF2123, PCA2125
[3]
UM10789 - USB-I²C-bus interface OM13518 with a GUI for the RTCs
[4]
PCF85063A - Tiny Real-Time Clock/calendar with alarm function and I²C-bus, data
sheet
[5]
PCF85063TP - Tiny Real-Time Clock/calendar and I²C-bus, data sheet
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8. Legal information
8.1 Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences
of use of such information.
8.2 Disclaimers
Limited warranty and liability — Information in this document is believed to
be accurate and reliable. However, NXP Semiconductors does not give any
representations or warranties, expressed or implied, as to the accuracy or
completeness of such information and shall have no liability for the
consequences of use of such information.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation lost profits, lost savings, business interruption, costs related to the removal
or replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability
towards customer for the products described herein shall be limited in
accordance with the Terms and conditions of commercial sale of NXP
Semiconductors.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP
Semiconductors accepts no liability for any assistance with applications or
customer product design. It is customer’s sole responsibility to determine
whether the NXP Semiconductors product is suitable and fit for the
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User manual
customer’s applications and products planned, as well as for the planned
application and use of customer’s third party customer(s). Customers should
provide appropriate design and operating safeguards to minimize the risks
associated with their applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from competent authorities.
Evaluation products — This product is provided on an “as is” and “with all
faults” basis for evaluation purposes only. NXP Semiconductors, its affiliates
and their suppliers expressly disclaim all warranties, whether express,
implied or statutory, including but not limited to the implied warranties of noninfringement, merchantability and fitness for a particular purpose. The entire
risk as to the quality, or arising out of the use or performance, of this product
remains with customer.
In no event shall NXP Semiconductors, its affiliates or their suppliers be
liable to customer for any special, indirect, consequential, punitive or
incidental damages (including without limitation damages for loss of
business, business interruption, loss of use, loss of data or information, and
the like) arising out the use of or inability to use the product, whether or not
based on tort (including negligence), strict liability, breach of contract, breach
of warranty or any other theory, even if advised of the possibility of such
damages.
Notwithstanding any damages that customer might incur for any reason
whatsoever (including without limitation, all damages referenced above and
all direct or general damages), the entire liability of NXP Semiconductors, its
affiliates and their suppliers and customer’s exclusive remedy for all of the
foregoing shall be limited to actual damages incurred by customer based on
reasonable reliance up to the greater of the amount actually paid by
customer for the product or five dollars (US$5.00). The foregoing limitations,
exclusions and disclaimers shall apply to the maximum extent permitted by
applicable law, even if any remedy fails of its essential purpose.
Translations — A non-English (translated) version of a document is for
reference only. The English version shall prevail in case of any discrepancy
between the translated and English versions.
8.3 Trademarks
Notice: All referenced brands, product names, service names and
trademarks are property of their respective owners.
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9. List of figures
Fig 1.
Fig 2.
Fig 3.
Fig 4.
Fig 5.
Fig 6.
Fig 7.
Block diagram of the PCx85063A ..................... 4
Interfacing to the microcontroller ....................... 5
Picture of demo board OM13515 ...................... 6
OM13515 circuit diagram .................................. 7
A) Dongle OM13518, B) connected to an
evaluation board ............................................... 8
GUI-page example: Time Alarm settings .......... 9
Temperature averaged over application range
5 °C to 45 °C ................................................... 12
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10. Contents
1.
2.
2.1
3.
3.1
3.2
4.
4.1
4.2
5.
5.1
5.2
5.3
5.3.1
5.3.2
6.
6.1
7.
8.
8.1
8.2
8.3
9.
10.
Introduction ......................................................... 3
Key features ......................................................... 3
PCx85063AT, PCF85063ATT ............................ 3
Hardware set-up .................................................. 5
General requirements for the RTCs PCx85063A5
Demo board OM13515 ....................................... 6
Graphical User Interface with OM13518 USBI²C-bus dongle ..................................................... 8
USB-I²C dongle .................................................. 8
Software GUI...................................................... 8
Software set-up ................................................... 9
Functionality ....................................................... 9
System testing.................................................. 10
Software instructions for setting the clock ........ 10
Setting the time ................................................ 10
Reading the clock ............................................. 11
RTC tuning ......................................................... 11
Frequency tuning ............................................. 11
References ......................................................... 13
Legal information .............................................. 14
Definitions ........................................................ 14
Disclaimers....................................................... 14
Trademarks ...................................................... 14
List of figures..................................................... 15
Contents ............................................................. 16
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in the section 'Legal information'.
© NXP B.V. 2014.
All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
Date of release: 4 August 2014
Document identifier: UM10788

UM10788 User manual for I²C-bus RTC demo board OM13515 User manual

Transcription

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